The increasingly common claim that President Trump is dismantling the U.S. Postal Service as a way of undermining mail-in voting and thus stealing the upcoming election is an example of one line of attack against President Trump, that he is so effective he can bend the government apparatus to his personal political will.
Yet that claim is in tension with another main line of attack by the Democrats against President Trump, the claim of incompetence. That is the claim made by Michelle Obama in her convention speech last night, "He is clearly in over his head."
Perhaps it is possible at least partially to reconcile these two claims—maybe Trump is ruthlessly effective when it comes to matters that affect directly his own personal or political interests, but hopelessly incompetent when it comes to matters of public interest, such as slowing the spread of the novel coronavirus (though surely at this point Trump has realized it would be good for his political fortunes if he could figure out a way to slow the spread of Covid-19). It's certainly theoretically possible for someone to be both malevolent and incompetent. Plenty of people even may think Trump is both. But as political messaging, these two lines of attack are inconsistent. The less competent Trump is, the less voters need to be concerned that he's plotting a fascist takeover, because the chances of him succeeding at it decrease.